The present invention relates generally to catheters and particularly to a lockable connector for drawing and maintaining the distal end of a catheter into a desired locked configuration.
Physicians currently use stabilizing structures to immobilize catheters and tubes within various body lumens, including the gastro-intestinal tract and the biliary duct. For example, suprapubic catheterization of the bladder is used to drain the bladder after surgery or when the genitourinary system is obstructed. Percutaneously inserted catheters are also used to drain the kidney or biliary system as well as to drain abscesses, or other areas of fluid collection, and other viscera. Still other percutaneously inserted catheters are employed as gastrostomy feeding tubes.
Typically, these catheters are introduced into the patient by means of a large hypodermic needle or trocar, which pierces the abdominal wall. A wire guide is inserted through the needle and then the needle is removed. A catheter tube having a stiffening cannula positioned therein is then passed over the wire guide into the cavity. The cannula and wire guide are then withdrawn, leaving the catheter in the desired cavity.
With respect to the bladder, the advantage of this technique is that irritation and infection of the urinary tract is minimized. However, one problem with these catheters is that the catheter may be easily pulled out by body movement, or by emptying of, for example, the bladder. Another problem is that side ports at the distal end of the catheter may be inadvertently drawn into the abdominal cavity, creating the potential for severe infections.
Various catheters have been developed with so-called pigtail loops at their distal ends for ensuring drainage of the cavity and preventing accidental removal therefrom. Generally, the pigtail loop is formed by pulling on a first end of a flexible tension member, for example, a suture, which extends through an inner lumen of the catheter. The second end of the tension member is secured to or within the catheter. The first end of the tensile member extends out of a first aperture near the distal end of the catheter and is looped back into the catheter through a second aperture disposed proximal of the first aperture. The first end of the tension member is then directed through the lumen towards the proximal end of the catheter for tightening. When the tensile member is pulled, it causes the distal end of the catheter to bend and assume a “pigtail” shape, which is larger than the aperture opened by the trocar, thus preventing the catheter from being accidentally removed.
While the pigtail configuration is commonly used to obtain the locked configuration of the distal end of the catheter, other configurations may also be used. For example, another locking configuration involves a catheter with axial cuts that subdivide the catheter tube into several sections. In these catheters, a tension member, such as a suture, attaches to the catheter tube at the distal end of the axial cuts, and when the tension member is tensioned the catheter axially shortens and the cut portions flare out to form an anchoring device. Regardless of whether a flared anchor or pigtail loop is used, the first end of the tension member may be held in place by any one of a number of retention means.
For example, the first end of the flexible tension member may be secured by axially placing a hollow cap into or over the first end of the catheter tube, thus trapping the flexible tension member in place and allowing the protruding first end to be cut. A problem with this catheter design is that once the protruding first end of the flexible tension member is cut, the hollow cap may slip or be inadvertently removed. As a result, the shortened flexible tension member moves distally, releases the pigtail, and is either difficult or impossible to retrieve. In another case, the flexible tension member is trapped between two or more hollow tubes, one of which is slidably inserted axially into the other. A short length of the flexible member is generally left hanging from the catheter tube so that if the flexible tension member becomes loose, it may be retightened. Alternatively, an external sleeve is slid over the flexible tension member protruding from the side of the catheter tube. This external sleeve may be located within an external locking device in which a lever arm with a cam may be used to press the sleeve tightly against the tension member to lock it in place. Disadvantageously, such devices enlarge the profile of the drainage catheter and require additional connections, thereby complicating the drainage procedure. Therefore, a need exists for a secure, easy to use, low profile tension member locking mechanism for use with drainage catheters.